Step 1 Cut the red onions into one-eighth-inch-thick slices. Set aside.
Step 2 In a medium bowl, whisk together the red wine vinegar, sugar, salt and pepper, making sure everything is dissolved
Step 3In a medium-sized heavy-bottomed pot, combine the onions and vinegar mixture. Cook over high heat, stirring occasionally, until the mixture is reduced by half and the onions are softened, light pink to purple in color and slightly translucent, about 30 minutes. Pour the mixture into a shallow glass baking dish and cool before using. This makes about 2 cups of Howie red onions.